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Search: id:A080692
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| A080692 |
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a(n)=(-1)^(n+1)*det(M(n)) where M(n) is the n X n matrix M(i,j)=min(abs(i-j),i). |
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1
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| 0, 1, 3, 8, 18, 40, 88, 192, 400, 832, 1728, 3584, 7424, 15360, 31744, 65536, 133120, 270336, 548864, 1114112, 2260992, 4587520, 9306112, 18874368, 38273024, 77594624, 157286400, 318767104, 645922816, 1308622848, 2650800128
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OFFSET
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1,3
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COMMENT
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A001787(n-1) is the determinant of the n X n matrix M(i,j)=min(abs(i-j),i+j)
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FORMULA
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a(n)=2*a(n-1)-2^floor(n-log(n)/log(2)-1)=2*a(n-1)-A054243(n)
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EXAMPLE
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M(5) is [0 1 1 1 1] [1 0 1 2 2] [2 1 0 1 2] [3 2 1 0 1] [4 3 2 1 0].
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PROGRAM
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(PARI) a(n)=(-1)^(n+1)*matdet(matrix(n, n, i, j, min(abs(i-j), i))
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CROSSREFS
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Cf. A054243, A001787.
Sequence in context: A135094 A026657 A036384 this_sequence A117080 A066425 A026679
Adjacent sequences: A080689 A080690 A080691 this_sequence A080693 A080694 A080695
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KEYWORD
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nonn
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AUTHOR
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Benoit Cloitre (benoit7848c(AT)orange.fr), Mar 03 2003
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